High-Tech Mining Makes Coal King of Fossil Fuels, But Is It Clean?

Oil may be getting the headlines lately, but it's coal that keeps our lights on. To find out how much has changed since the days of canaries and shovels, we went underground for a look at the working conditions of the modern coal miner. (Click here for the seven steps that make rock into energy-efficient gas)

It's 10 am on a Wednesday in February and the eastern United States is covered with snow and ice. Schools are closed, flights delayed, interstates barely open. But light bulbs need to be lit and laptops need powering. So Frank Dankovich and Doug Conklin suit up for another day at the office: steel-toed rubber boots; layers of warm clothing; hard hats and headlamps; belts heavy with emergency breathing apparatus, gas meters and two-way radios. Their workplace is capricious and not to be trifled with. Each man hangs a copper tag on a board, slips a copy of a matching tag in his pocket -- "God forbid," someone mutters -- and enters an elevator that drops deep into southwestern Pennsylvania's Emerald Mine, a bone-chilling, subterranean world that few people ever see or even think about, unless the muttered prayer fails. "It's a factory floor," says Conklin, Emerald's general manager, a wiry, intense man with 29 years underground. "Except you're dealing with rushing water and rolling coal faces."

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When the elevator door swings open 625 ft. below the wintry landscape, I expect to see an underground city. Instead, there is only a white-walled tunnel, stark in the cold fluorescent glare. About 100 yards into the tunnel the lights end; beyond, there's nothing but darkness, filled with a shivering wind.

Our Favorite Fossil Fuel

Few things seem as anachronistic as an underground coal mine. Black-faced miners in lamps and hard hats; coal trains and company towns -- the images are seared in our brains and in our folklore. Images of an old smokestack economy that's largely been supplanted by the industrial might of the semiconductor. Except that all those computers, HDTVs, groovy little iPods and other silicon-chip wonders would fall silent if it weren't for coal. Wind, water, nuclear, oil, natural gas, solar energies -- add them all up and together they barely produce as much electricity as coal.

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Last year, America consumed more than 1 billion tons of the mineral. At the present rate, using existing extraction technology, the reserves will last 243 years. Coal is dramatically cheap to mine, too: In 2005 it cost $8.66 to produce a million BTU of oil; the equivalent energy from coal cost $1.19. About two-thirds of America's favorite fossil fuel comes from surface mines (about 778 million tons); the rest is produced in underground mines, mainly in Appalachia.

Much of the eastern coal is found in narrow seams hundreds of feet below ground. Emerald, which is one of 14 U.S. mines owned by Foundation Holdings, works the Pittsburgh seam, an 8-ft.-thick bed that extends thousands of square miles below four states. Emerald itself is vast: Its underground footprint covers more than 100 square miles, and its output is prodigious -- nearly 7 million tons in 2006.

Gone are the picks, the shovels and the canaries: Mining in Emerald and other underground operations has undergone a profound technological change. In the room-and-pillar method, tunnels as high as the seam is thick are bored around large blocks of coal that help hold the roof in place. But the technique -- long dominant in Appalachia -- can be inefficient, leaving behind as much as 65 percent of the recoverable coal in pillars that are bigger than the rooms they support.

Most companies working thick, flat-lying beds now use a much more efficient extraction method called longwall mining, which was first developed in England in the 1600s and introduced to Appalachia in the 1950s. In the past 15 years longwall equipment has become vastly larger and more reliable, making for huge productivity gains. First, an electrically powered tracked vehicle called a continuous miner uses a 16-ft.-wide rotating drum cutter on its front end to tunnel through a seam in a room-and-pillar pattern. The primary objective: Isolate huge rectangles of coal, known as panels. (In the Emerald mine panels are up to 2 miles long and 1250 ft. wide -- the widest in North America.) As the toothed cutting wheel grinds through the seam, coal spits out the back end, where a tracked conveyor scoops it up. It takes only three men to operate the continuous miner, which can advance 210 ft. per day.

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Longwall Mining
About 33 percent of all underground coal production in the U.S. comes from longwall mining. A continuous mining machine is used to isolate huge rectangular panels that are extracted by an automated shearer moving back and forth along the face. Here's how it all works. -- Erin McCarthy

Diagram by Dogo

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[1]Continuous miners perform room-and-pillar operations, which isolate longwall panels and provide passages for workers and for conveyor belts used to transport coal to the surface.

[3]Coal panels are up to 1250 ft. wide and 10,560 ft. long. Removing an average of 60 ft. of coal per day, a longwall shearer can mine a single panel in six months.

[5] To reach the surface, coal travels on a conveyor belt through the slope tunnel, which also contains rails for transporting equipment. single panel in six months.

%" style="font-size:8pt; padding:2px; background-color:#d5e6f1;">[2] An operator walks alongside the longwall shearer, directing it with a handheld remote control as it moves along a track parallel to the working coal face. Twin rotating drums slice off coal to a depth of 312 ft. with each pass. Hydraulic ceiling shields protect miners. As the shearer advances, the unsupported roof gradually collapses behind it.

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[4] A series of conveyor belts, some as long as 2.5 miles, moves coal through the mine and to the surface at a speed of about 10 mph.

[6]Aboveground, rocks are removed from the coal, which is sorted by size before distribution.

Once a panel has been prepped, a longwall machine is set to work. At Emerald, this single piece of equipment produces 95 percent of the mine's output. An automated shearer with twin cutting heads moves back and forth across the working face of a panel, gnawing off chunks of black rock with each pass. If used on two daily shifts, Emerald's longwall machine can eviscerate a 352-acre panel in about six months.

Longwall mining is not only highly efficient in terms of coal extraction; it uses far fewer miners than are required for room-and-pillar. "When I started 33 years ago," says Dankovich, 56, "you'd have 1200 people underground and you'd be lucky to mine 1 million tons of coal a year. Now we've got 150 people down there at any given time and we're pulling out over six times that."

Mining these huge panels doesn't come without a cost, however. Underground mining causes what's known as subsidence -- the land above a mine settles -- but since longwall mining leaves behind no pillars as a panel is excavated, the empty space created by the longwall machine eventually collapses, which can cause the ground above to subside as much as 4 ft. Buildings, roads, streams, every surface feature is altered. "Longwall mining is particularly destructive," says Stephen P. Kunz, a senior ecologist at Schmid & Company, a Pennsylvania­-based consulting firm. "It's like a slow-moving earthquake that can dry streams, wetlands and wells over thousands of acres, and it is not factored into the price of coal."

The Snake at the Face

A hundred yards down the tunnel from the elevator, we climb into a mantrip -- a 4-ft.-high diesel-powered vehicle on rails. The operator dials a four-digit number to report who we are and where we're headed to aboveground monitors. As soon as we rumble down the tracks we are engulfed in darkness; the only light comes from our battery-operated headlamps.

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It's hard not to think about what could go wrong down in a mine. In 1988 Dankovich was trapped in a mine fire. "You couldn't see your hand in front of your face," he says. "I beat 10 years off my heart in the hour it took us to walk out through the smoke. You have a lump in your throat, thinking about your wife and kids. We all made it out but some guys never went back in."

Despite a slight increase in U.S. mining accidents in 2005 and 2006, underground mining is far safer than it used to be -- declining from an average of more than 2400 deaths a year in the early 20th century to 47 last year. Strung overhead in Emerald's tunnels is a fiberoptic cable feeding information about every fan, hydraulic machine and conveyor to management; a UHF antenna enables two-way radio communication. The walls and floors are covered with crushed limestone to suppress flammable coal dust. Miners and machines are equipped with gas sensors, and six huge fans circulate fresh air throughout the mine.

We trundle along at about 10 mph, passing dark turnoffs and "manholes" -- small indentations in the wall just large enough for a miner to stand in to avoid getting sideswiped by the mantrip. When the tracks end we take an eerie walk through cold and darkness, toward the bob of headlamps. We come upon men tending rows of ­machinery -- the brains, nervous system and vascular system of the longwall machine. It's mostly electric and hydraulically powered, but, since conventional hydraulic fluid is flammable, the fluid down here is an emulsion of 5 percent oil and 95 percent water. The line of equipment -- known as the mule train -- is moved every nine or 10 days as the working face advances. There is barely enough room in the tunnel to squeeze by.

The closer we get to the face the hotter it grows and the more miners we encounter. Then there's a sound. A distant din, a thumping, a roar that grows as we turn left down a crosscut and emerge 100 ft. later into a parallel tunnel that houses a conveyor belt running so fast it takes a few seconds to make out coal flying past at 930 ft. per minute. It's a 7-mile conveyor journey to the surface, and because the mine face advances 60 ft. every 24 hours, the conveyor has to be moved that far, too. "Imagine buying a Cadillac," Conklin shouts, "taking it apart in your garage, moving it a few blocks to your buddy's garage, putting it all back together again and then taking your family for a drive. That's what we do in here every day!"

In Emerald's longwall operation, continuous mining machines are used to bore connecting tunnels through the coal seam -- as much as 210 ft. per day -- and to install 8-ft.-long steel roof bolts anchored in epoxy resin.

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We follow the conveyor and then, half an hour after leaving the elevator, we're there: the mine face. It is an almost inconceivable place, a combination of Starship Enterprise and Mordor -- a colossal iron snake lying in thick mud and stretching the length of four football fields. The longwall machine consists of 251 adjacent "shields," each of which weighs 24 tons and can withstand 900 tons of pressure. The hydraulic awning of each 5-ft.-high shield supports the rock overhead; the machine rests on 251 pairs of hydraulic feet. Dankovich operates the shearer -- two 4-ft.-wide spinning drums, one above the other, that move on sprockets along the face of jet-black coal. They shear off a swath 6 ft. high and 3.5 ft. deep -- up to 18 tons a minute -- as six jets of water spray the drums to keep down the dust. The coal falls onto a conveyor. When a pass is complete there's a tremendous clang as the awnings holding the roof in place lower, the big feet slide forward, and the roof clangs in place again. Then the shearer reverses direction. Pass by pass, the machine frees some 26,000 tons of raw energy every 24 hours.

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Dankovich started working the longwall equipment 12 years ago. Hiking through the muck as he follows the shearer moving along the face, he shouts, "If you got seven passes in a week it was remarkable. We used to have a lot of breakdowns. Now it's seven passes in an 8-hour shift. It just runs and runs."

When this panel is mined, the whole machine will be disassembled and moved to the next panel, a process that can take as few as 11 days. A single longwall machine of this size costs $70 million, but at current coal prices, it pays for itself in about two months. Foundation plans to install a second one in the Emerald mine.

All this production technology helps keep coal cheap. But electricity consumption is rising -- and is expected to double in the next 30 years. To keep pace with demand, 150 coal-fired power plants are slated for construction in the United States. There's only one problem with this bounty of energy under our feet: Coal use injects vast amounts of carbon dioxide into the air, along with nitrous oxide, sulfur dioxide and mercury. Eighty percent of the CO2 emitted by generating electricity in the United States comes from coal, and it's likely that in the near future the federal government will start regulating greenhouse gases. In April 2007 the U.S. Supreme Court held that the U.S. Environmental Protection Agency had the power to regulate CO2 as it would any other pollutant.

The dream is to turn coal into a clean fuel. In a billion-dollar project called FutureGen, the Department of ­Energy and coal companies are building a 275-megawatt, coal-fired power plant that will generate electricity and hydrogen, while sequestering CO2 to nearly eliminate emissions.

One of the technologies slated for FutureGen, known as integrated gasification combined cycle (IGCC), turns coal into gas before combustion, dramatically reducing most emissions. Except CO2, that is. But it can be captured. The debate among power companies is whether it's cheaper to do it with IGCC plants -- which are more expensive to build -- or with conventional plants that burn pulverized coal. Earlier this year, in the name of energy independence, lawmakers began drafting legislation that would champion a different technology: One that transforms coal into liquid fuel. Some proposals in the bills include construction loan guarantees for six to 10 production plants, costing at least $1 billion each; extending tax credits on coal-based fuel sold through 2020; minimum prices; and long-term government purchases for the next 25 years.

But when it comes to coal, the goal of energy independence clashes with efforts to reduce global warming. Environmental groups claim that the coal-to-liquid process produces twice the carbon dioxide of burning a gallon of diesel. The coal-based liquid also generates the greenhouse gas when used in cars.Other critics point to the failed taxpayer-funded industrial policy of the 1970s that was supposed to jumpstart a synthetic fuel industry.

Whatever happens, the black rock's sheer abundance will keep it the fossil fuel of choice for power plants for years to come. Every time you turn on your lights or your laptop, it's thanks in part to an underground miner and a place like Emerald -- out of sight, out of mind. A place of intense hazard and camaraderie, of men working in the cold and darkness, relying upon technology and, yes, upon themselves for their safety. "I know my dangers and what's in front of me," says Dankovich, who's been underground six days a week for more than three decades. "But in the `outby' [away from the working face], I depend on the others to be alert and to warn me if anything goes wrong."

To bolster the ceiling supports installed by the continuous mining machine, miners brace the ceiling beams with additional steel rods. (The heads and upper shafts can be seen on the right.)

The cutting drum of a 45-ft.-long shearer -- the business end of a longwall mining machine -- grinds a swath of coal 6 ft. high and 3.5 ft. deep from the face of the Emerald mine, in southwestern Pennsylvania. Thanks to longwall machines, Appalachia's underground mines are producing record amounts of coal.